In manufacturing petroleum pitch, it is known to air blow a petroleum residuum while maintaining the temperature at about 650.degree.-750.degree. F. The procedure is very tedious, requiring a long duration of action in order to bring the material to useable characteristics of high melting point and low penetration.
Several attempts have been made to add catalysts to enhance the air blowing operation. In Fink et al, U.S. Pat. No. 2,627,498, granted Feb. 3, 1953, it was proposed to first add metal halide catalyst and then air blow; and in Thelen, U.S. Pat. No. 2,281,728, granted May 5, 1942, it was proposed to first treat the feedstock with hydrochloric acid prior to air blowing; while in Pitchford et al, U.S. Pat. No. 3,919,072, granted Nov. 11, 1975, metal chlorides are mentioned as catalysts for pre-treatment of the feedstock before air blowing, for producing asphalts.
Burk et al, U.S. Pat. No. 2,179,208, granted Nov. 7, 1939, discloses air blowing of petroleum residuum wherein, in a post heat treatment a catalyst is used for producing an asphalt. A broad list of catalysts is disclosed, the preferred catalysts being metal halides and inorganic acids, and although metallic sodium is disclosed, it is not preferred.
There is no indication in the prior art of the effectiveness of metallic sodium in the concentrations as disclosed, herein, for producing a high grade pitch at a faster production rate.
It is therefore a principal object of this invention to provide an improved method of obtaining pitch from petroleum bottoms.
It is another object of this invention to provide a method as aforesaid wherein petroleum bottoms are air blown with a reduced residence time than heretofore.
It is still another object of this invention to provide a method as aforesaid in which the product pitch has a high density.
It is also a further object of this invention to produce a high density petroleum pitch by a method that is practical and efficient in design and operation, and provides a reduction in the equipment requirements for pitch production.